Groundwater prevention and control device and method for valley-type historical remaining pollution source

Abstract

The invention relates to the technical field of environmental remediation, and discloses a valley type historical remaining pollution source underground water prevention and control device and method.The prevention and control device comprises an anti-scour panel and a water retaining wall which are laid on the surface of a valley and used for achieving diversion of surface water and underground water; and water inlet and outlet area water guide walls are arranged below the earth surface. Polluted underground water is intercepted by combining a water inlet side with a peripheral waterproof curtain, and all the polluted underground water is introduced into the buried PRB pool. Holes are formed in the PRB pool in a staggered mode through partition walls to guide water flow to form up-down baffling, a reduction area, an oxidation area and an adsorption fixing area are arranged along the way, and assembly type modular stuffing boxes capable of being hoisted, unloaded and replaced are arranged in all the areas. According to the invention, sewage disposal diversion and unpowered water catchment are realized, and graded purification is carried out on combined pollution; the modular filler is combined with on-line monitoring, so that the defects that the traditional filler is easy to block and difficult to replace are overcome, and the water quality safety of underground water is guaranteed for a long time.

Description

Technical Field

[0001] This invention relates to the field of environmental remediation technology, specifically to a groundwater control device and method for valley-type historical pollution sources. Background Technology

[0002] Currently, the leaching water, abandoned mine water, and landfill leachate, which contain high concentrations of heavy metals and organic pollutants, generated in concentrated pollution sources such as mine tailings ponds, waste slag landfills, and landfills, often enter surrounding water bodies and farmland through surface runoff and groundwater seepage, resulting in serious pollution of groundwater quality.

[0003] Permeable reactive barrier (PRB) technology, as an emerging green and low-carbon pollution control technology, boasts advantages such as low energy consumption, simple management, and long-term treatment of contaminated groundwater. However, existing traditional PRB reactive media are typically monolithic, permanent, and difficult to replace. As pollutants flow through the activated media zone with groundwater, the activity of the media gradually decreases as the reaction proceeds. These deactivated media not only pose a potential secondary pollution source to groundwater but also cause pore blockage in the reactive media. Once blockage occurs, the pollutant plume will bypass the blocked reactive media, making it difficult to guarantee the long-term effectiveness of groundwater remediation. Summary of the Invention

[0004] To address the groundwater pollution problem caused by surface runoff and groundwater infiltration from historical pollution sources in valley terrain, this invention provides a groundwater control device and method for valley-type historical pollution sources. The aim is to intercept and collect contaminated groundwater through specific interception and barrier structures, and to overcome the technical shortcomings of traditional PRB reactive packing materials, such as easy clogging, difficulty in replacement after deactivation, and the risk of secondary pollution, by utilizing graded and zoned prefabricated modular packing materials. This achieves long-lasting and efficient groundwater purification. The specific technical solution is as follows: A groundwater control device for a valley-type historical pollution source, wherein the groundwater control device is installed in a valley downstream of the historical pollution source, characterized in that the groundwater control device comprises: The erosion control panels for the inlet and outlet areas are laid on the surface of the gully at the upstream end and the erosion control panels for the outlet area, respectively. These panels are used to guide surface runoff and separate surface water from groundwater. The inlet erosion control panel has a water-facing end and a water-facing end, with the water-facing end bent downwards and embedded in the ground. The water inlet zone water guide wall is located at the end of the water inlet zone anti-erosion panel and extends into the ground to collect the infiltrated contaminated groundwater. A water-retaining wall is installed at the end of the anti-erosion panel in the water inlet area and located on the ground surface to block surface water and buffer water storage. The PRB pool is located underground downstream of the retaining wall. The PRB pool is equipped with a modular packing box. The water inlet guide wall is abutted against and connected to the upstream water inlet side of the PRB pool. The groundwater collected therein flows into the PRB pool for purification treatment. A water-stopping curtain, wherein the water-stopping curtain is arranged in the strata below the upstream inlet side of the PRB pool and in the strata of the mountains on both sides, is used to intercept the contaminated groundwater and guide it to flow entirely through the PRB pool; and The water outlet zone guide wall is located underground, downstream of the PRB pool and below the anti-erosion panel of the water outlet zone. The water outlet zone guide wall is connected to the downstream water outlet side of the PRB pool and is used to discharge the groundwater purified by the PRB pool.

[0005] In a preferred embodiment, the PRB pool is a graded and zoned underground structure, which is provided with an inlet zone, a reduction zone, an oxidation zone, an adsorption and fixation zone and an outlet zone in sequence along the water flow direction, and a gate is provided between the inlet zone and the reduction zone. The assembled modular packing boxes are placed in parallel within the reduction zone, oxidation zone, and adsorption fixation zone.

[0006] In a preferred implementation, the PRB pool further includes an upstream outer wall, a downstream outer wall, and multiple internal partitions that divide the PRB pool into the inlet zone, reduction zone, oxidation zone, adsorption and fixation zone, and outlet zone. Water passages are provided in the upstream outer wall, the downstream outer wall, and each of the internal partition walls; The water passage located on the upstream outer wall is opened at the lower part near the bottom plate of the PRB pool and is connected to the water guide wall of the inlet area; the water passage located on the downstream outer wall is opened at the upper part near the top plate of the PRB pool and is connected to the water guide wall of the outlet area. The water passages located on the internal partition walls are staggered at the top or bottom of each internal partition wall to guide the groundwater to form vertical flow between the partitions, and to make the overall groundwater flow direction of the PRB pool be downward inflow and upward outflow. Furthermore, steel mesh for sealing the holes is fixedly installed at the water passages corresponding to the upstream outer wall of the water inlet area and the downstream outer wall of the water outlet area.

[0007] In a preferred embodiment, the top of the PRB pool is provided with a concrete cover plate and a water-stop rubber plate from top to bottom; The concrete cover plate is equipped with hooks for lifting and replacing the prefabricated modular filling box.

[0008] In a preferred embodiment, online monitoring equipment is installed in both the inlet and outlet zones of the PRB pool to monitor the concentration of pollutants in the groundwater in real time.

[0009] In a preferred embodiment, the interior of both the inlet and outlet water guide walls is filled with pebbles with a particle size of 20mm to 40mm, and the exterior is covered with non-woven geotextile. The bottom of the water-conducting wall in the water inlet area is covered with a compacted clay water-stopping layer, which is connected to the water-stopping curtain to seal the groundwater infiltration channel.

[0010] In a preferred embodiment, both the inlet anti-scouring panel and the outlet anti-scouring panel are plain concrete panels with a thickness of not less than 100 mm. A gravel backfill layer is provided under the anti-scouring panel of the water inlet area, and the bottom of the gravel backfill layer is flush with the bottom of the water guide wall of the water inlet area. The retaining wall is a plain concrete wall, and its height is at least 500mm above the ground level of the ditch.

[0011] In a preferred implementation, the bottom of the water-stop curtain extends downward into the underground weakly weathered rock layer, and its two sides extend outward into the interior of the mountain strata.

[0012] A method for controlling groundwater pollution from a valley-type historical pollution source based on any of the above-mentioned control devices includes the following steps: Step 1: Use the anti-erosion panels in the inlet and outlet areas laid on the ground to guide surface runoff and reduce surface water infiltration; at the same time, use the retaining wall to intercept surface flash floods and buffer and store water. Step 2: The contaminated groundwater that has infiltrated is collected by the water-conducting wall in the inlet area. With the combined guiding and blocking effect of the compacted clay at the bottom and the surrounding water-stopping curtain, all the contaminated groundwater is introduced into the buried PRB pool. Step 3: The groundwater entering the PRB pool flows sequentially through the inlet zone, reduction zone, oxidation zone, and adsorption and fixation zone. The heavy metals and organic matter in the groundwater are reduced, oxidized, and adsorbed and fixed in stages through the internal prefabricated modular packing box. Step 4: The purified groundwater enters the outlet area. After passing the online monitoring equipment test and meeting the standards, it is discharged into the downstream environment through the water guide wall in the outlet area.

[0013] In a preferred implementation, in step four, the pollutant concentrations in the inlet and outlet water zones are compared in real time using the online monitoring device to assess the reactivity of the packing material in the prefabricated modular packing box. When monitoring data indicates that the activity of the packing material has decreased, causing the effluent water quality to approach the critical value of exceeding the standard, the concrete cover plate on the top of the PRB tank is opened, the deactivated prefabricated modular packing box is lifted out as a whole and replaced with a new packing box.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention utilizes the anti-erosion panel of the water inlet and outlet zone on the surface to realize the diversion of surface water and groundwater, increase the surface water runoff, and reduce the amount of polluted groundwater to be treated due to the infiltration of surface water from the source.

[0015] (2) By cleverly utilizing the valley terrain, the device collects contaminated groundwater without power by relying on gravity flow and water level difference; compared with traditional PRB, the device has a shallow excavation depth, low construction cost, and less disturbance to the geological structure of the natural groundwater flow field. (3) The use of modular prefabricated stuffing boxes and online monitoring equipment completely solves the problems of flow channel blockage and secondary pollution that are easily caused by the deactivation of traditional PRB integral stuffing. The stuffing box is easy to lift and replace, ensuring long-term and efficient repair results.

[0016] (4) The PRB pool forms an up-and-down flow and is divided into reduction zone, oxidation zone and adsorption and fixation zone, which can solve the problem of heavy metal and organic compound pollution in historical pollution sources in a graded, batch-by-batch and synchronous manner. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a schematic diagram of the planar structure of the groundwater control device for valley-type historical pollution sources of the present invention.

[0019] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure at point AA.

[0020] Figure 3 This is a schematic diagram of the assembled stuffing box in this invention.

[0021] In the diagram: 1. Anti-scouring panel in the inlet area; 2. Water guide wall in the inlet area; 3. Water retaining wall; 4. PRB pool; 401. Steel mesh; 402. Water passage; 403. Inlet area; 404. Gate; 405. Reduction zone; 406. Oxidation zone; 407. Adsorption and fixation zone; 408. Prefabricated modular packing box; 409. Concrete cover plate; 410. Water-stop rubber plate; 411. Outlet area; 5. Water-stop curtain; 6. Water guide wall in the outlet area; 7. Anti-scouring panel in the outlet area; 8. Internal partition; 9. Crushed stone backfill layer; 10. Compacted clay water-stop layer. Detailed Implementation

[0022] The present invention will be further described below through specific embodiments, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the protection scope of the present invention.

[0023] like Figures 1 to 3 As shown, this embodiment of the invention provides a groundwater control device for historical pollution sources in valley-type terrain. It is mainly used to address groundwater pollution problems that may be caused by historical pollution sources in valley-type terrain (such as mine tailings ponds, waste slag landfills, and garbage landfills). The device utilizes the valley terrain, employing erosion-resistant panels to separate surface water from groundwater, and uses a buried PRB pool 4, a water-stop curtain 5, and a prefabricated modular packing box 408 to collect and classify the polluted groundwater for purification.

[0024] like Figure 1 and Figure 2 As shown, this invention discloses a groundwater control device for a valley-type historical pollution source. The groundwater control device is installed in the valley downstream of the historical pollution source and includes an inlet scour protection panel 1 and an outlet scour protection panel 7. The inlet scour protection panel 1 and the outlet scour protection panel 7 are located on the surface of the upstream and downstream ends of the valley, respectively. In this embodiment, both are made of plain concrete panels with a thickness of not less than 100 mm. Of course, it is understood that the material and size of the inlet scour protection panel 1 and the outlet scour protection panel 7 can be set according to actual conditions. The inlet scour protection panel 1 has a water-facing end and an outlet end. The water-facing end is bent downward and embedded in the ground, and a gravel backfill layer is placed under the inlet scour protection panel 1. A water-retaining wall 3 is set at the surface of the outlet end of the inlet scour protection panel 1. The water-retaining wall 3 is a plain concrete wall with a height at least 500 mm above the bottom of the valley, used to buffer water and prevent flash flood erosion.

[0025] An underground water-conducting wall 2 is installed below the end of the erosion-resistant panel 1 in the inlet area to collect infiltrated contaminated groundwater. The bottom of the aforementioned crushed stone backfill layer is flush with the bottom of the water-conducting wall 2. Both the water-conducting wall 2 in the inlet area and the water-conducting wall 6 in the outlet area downstream are filled with pebbles with a particle size of 20mm to 40mm and covered with non-woven geotextile.

[0026] In particular, such as Figure 2 As shown at the bottom, a compacted clay waterstop layer is laid at the bottom of the water inlet zone water guide wall 2. This compacted clay waterstop layer works together with the waterstop curtain 5 below it to seal the groundwater infiltration channel, so that all the infiltrated contaminated groundwater is collected and forcibly guided into the PRB pool 4 behind it.

[0027] A buried PRB pool 4 is installed underground downstream of the retaining wall 3. The inlet guide wall 2 abuts against and connects to the upstream inlet side of the PRB pool 4, while the outlet guide wall 6 is located downstream of the PRB pool 4, underground below the outlet scour protection panel 7, and connected to the downstream outlet side of the PRB pool. To prevent groundwater from escaping downstream, such as... Figure 2 As shown, a row of water-stopping curtains 5 are arranged in the strata below the upstream water inlet side of PRB pool 4 and in the strata of the mountains on both sides. The bottom of the water-stopping curtains 5 extends downward into the underground weakly weathered rock layer, and its two sides extend outward into the interior of the mountain strata.

[0028] Key reference Figure 2 The dashed water flow path in the diagram indicates that the PRB tank 4 is a graded and zoned structure, with an inlet zone 403, a reduction zone 405, an oxidation zone 406, an adsorption and fixation zone 407, and an outlet zone 411 arranged sequentially along the water flow direction. A gate 404 is installed between the inlet zone 403 and the reduction zone 405. The PRB tank 4 has an upstream outer wall, a downstream outer wall, and multiple internal partition walls 8 that divide the tank into the aforementioned functional zones.

[0029] like Figure 2 The layout of the water passages 402 shown has the following configurations: the water passage 402 on the upstream outer wall is located near the bottom of the PRB pool 4 and connects to the inlet guide wall 2; the water passage 402 on the downstream outer wall is located near the top of the PRB pool 4 and connects to the outlet guide wall 6. Simultaneously, the water passages on each internal partition wall 8 are staggered, located at the top or bottom of the partition wall. This spatial perforation layout guides groundwater to form a pattern between the different zones. Figure 2 The "upward and downward flow" path shown by the dashed line makes the overall groundwater flow direction of PRB pool 4 "downward inflow and upward outflow". In order to prevent the loss of external filler, steel mesh 401 for sealing is fixedly installed only at the water passage 402 on the upstream outer wall of the inlet zone 403 and the downstream outer wall of the outlet zone 411.

[0030] Modular prefabricated packing boxes 408 are placed in parallel within the reduction zone 405, oxidation zone 406, and adsorption / fixation zone 407. These modular packing boxes 408 feature a mesh structure design, facilitating water flow while confining the internal reactive packing material. The top of the PRB tank 4 is topped with a concrete cover 409 and a water-stop rubber plate 410, arranged sequentially from top to bottom. The concrete cover 409 is equipped with a hook; when online monitoring equipment in the inlet zone 403 and outlet zone 411 detects packing material deactivation, the concrete cover 409 can be opened, and the modular prefabricated packing box 408 can be lifted and replaced entirely using the hook.

[0031] Another objective of this invention is to provide a groundwater control method based on the aforementioned control device, the specific steps of which are as follows: Step 1: Use the anti-scour panels 1 in the inlet area and the anti-scour panels 7 in the outlet area laid on the ground to guide the surface runoff; use the retaining wall 3 to intercept surface flash floods and buffer and store water.

[0032] Step 2: The contaminated groundwater is collected by the water guide wall 2 in the inlet area and introduced into the PRB pool 4 under the interception of compacted clay and water-stop curtain 5.

[0033] Step 3: Combining Figure 2 The water flow direction is as follows: groundwater flows through the inlet zone 403, gate 404, reduction zone 405 (reduction of variable valence metals such as Cr6+ and chlorinated organics), oxidation zone 406 (oxidation of variable valence metals such as As3+ and organics), and adsorption and fixation zone 407 (adsorption and precipitation of toxic metal ions).

[0034] Step 4: The purified groundwater enters the effluent zone 411. After meeting the standards, it is discharged downstream through the effluent zone guide wall 6. During operation, based on the water quality data fed back by the online monitoring equipment, the deactivated prefabricated modular packing box 408 is hoisted out and replaced in a timely manner through the top opening.

[0035] Specific implementation examples: This invention is based on a pollution control project involving antimony and other heavy metals. Measurements showed that the antimony exceedance rate in the groundwater downstream of the upstream slag heap was 100% (maximum exceedance 17.8 times), and the arsenic exceedance rate was 66.7%. This control device was constructed in the valley. The design uses a water-stop curtain 5 in the form of 800mm diameter high-pressure jet grouting piles to cut off the groundwater channel. The calculated daily groundwater volume is 9.85 m³ / h. The PRB pool 4 is designed as a reinforced concrete structure with L×B×H=4.30m×3.25m×2.75m. Six sets of [unspecified equipment] are installed within the pool. Figure 3 The modular stainless steel packing box 408 shown (single set dimensions 1.40m × 0.55m × 2.75m) is filled with composite adsorbent material. The packing material is dynamically replaced based on online monitoring data of the influent and effluent, effectively preventing continuous pollution of the downstream reservoir by groundwater.

[0036] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A groundwater control device for a valley-type historical pollution source, wherein the groundwater control device is installed in a valley downstream of the historical pollution source, characterized in that, The groundwater control device includes: The inlet erosion control panel (1) and the outlet erosion control panel (7) are provided. The inlet erosion control panel (1) is laid on the surface of the upstream end of the gully, and the outlet erosion control panel (7) is laid on the surface of the downstream end of the gully. The inlet erosion control panel (1) and the outlet erosion control panel (7) are used to guide surface runoff and realize the separation of surface water and groundwater. The inlet erosion control panel (1) has a water-facing end and an end end, and the water-facing end is bent downward and embedded in the ground. Water inlet zone guide wall (2), the water inlet zone guide wall (2) is set at the end of the water inlet zone anti-scour panel (1) and extends into the ground, for collecting the infiltrated contaminated groundwater; Water retaining wall (3), the water retaining wall (3) is set at the end of the anti-scour panel (1) in the water inlet area and is located on the ground surface, for blocking surface water and buffering water storage; PRB pool (4), the PRB pool (4) is located underground downstream of the water retaining wall (3), the PRB pool (4) is equipped with a modular packing box (408), the water inlet area guide wall (2) abuts against and connects to the upstream water inlet side of the PRB pool (4), and the groundwater collected therein flows into the PRB pool (4) for purification treatment. Water-stopping curtain (5) is arranged in the strata below the upstream inlet side of the PRB pool (4) and in the strata of the mountains on both sides, to block the polluted groundwater and guide it to flow through the PRB pool (4). Water outlet guide wall (6) is located underground downstream of the PRB pool (4) and below the water outlet anti-erosion panel (7). The water outlet guide wall (6) is connected to the downstream water outlet side of the PRB pool (4) and is used to discharge the groundwater purified by the PRB pool (4).

2. The groundwater control device for valley-type historical pollution sources according to claim 1, characterized in that, The PRB pool (4) is a graded and zoned buried structure, which is provided with an inlet zone (403), a reduction zone (405), an oxidation zone (406), an adsorption and fixation zone (407) and an outlet zone (411) in sequence along the water flow direction. A gate (404) is provided between the inlet zone (403) and the reduction zone (405). The assembled modular packing box (408) is placed in parallel within the reduction zone (405), oxidation zone (406), and adsorption and fixation zone (407).

3. The groundwater control device for valley-type historical pollution sources according to claim 2, characterized in that, The PRB pool (4) also includes an upstream outer wall, a downstream outer wall, and multiple internal partitions (8) that divide the PRB pool (4) into the inlet zone (403), reduction zone (405), oxidation zone (406), adsorption and fixation zone (407) and outlet zone (411). Water passages (402) are provided on the upstream outer wall, the downstream outer wall, and each of the internal partition walls (8). Among them, the water passage located on the upstream outer wall is opened at the lower part near the bottom plate of the PRB pool (4) and is connected to the water guide wall (2) of the water inlet area; the water passage located on the downstream outer wall is opened at the upper part near the top plate of the PRB pool (4) and is connected to the water guide wall (6) of the water outlet area. The water passages located on each of the internal partition walls (8) are staggered at the top or bottom of each of the internal partition walls (8) to guide the groundwater to form vertical flow between each partition, and to make the groundwater flow direction of the PRB pool (4) as a whole downward inflow and upward outflow. Furthermore, steel mesh (401) for sealing holes is fixedly provided at the water passage (402) corresponding to the upstream outer wall of the water inlet area (403) and the downstream outer wall of the water outlet area (411).

4. The groundwater control device for valley-type historical pollution sources according to claim 1, characterized in that, The top of the PRB pool (4) is provided with a concrete cover plate (409) and a water-stop rubber plate (410) from top to bottom. The concrete cover plate (409) is equipped with a hook for lifting and replacing the prefabricated modular filling box (408).

5. The groundwater control device for valley-type historical pollution sources according to claim 2, characterized in that: The PRB pool (4) is equipped with online monitoring equipment in both the inlet zone (403) and the outlet zone (411) to monitor the concentration of pollutants in the groundwater in real time.

6. The groundwater control device for valley-type historical pollution sources according to claim 1, characterized in that: The water inlet guide wall (2) and the water outlet guide wall (6) are both filled with pebbles with a particle size of 20mm to 40mm and covered with non-woven geotextile. The bottom of the water-conducting wall (2) in the water inlet area is covered with a compacted clay water-stopping layer, which is connected to the water-stopping curtain (5) to seal the groundwater infiltration channel.

7. The groundwater control device for valley-type historical pollution sources according to claim 1, characterized in that: The anti-scouring panel (1) in the water inlet area and the anti-scouring panel (7) in the water outlet area are both plain concrete panels with a thickness of not less than 100mm; A gravel backfill layer is provided under the anti-scouring panel (1) of the water inlet area, and the bottom of the gravel backfill layer is flush with the bottom of the water guide wall (2) of the water inlet area. The retaining wall (3) is a plain concrete wall, and its height is at least 500mm above the ground at the bottom of the ditch.

8. The groundwater control device for valley-type historical pollution sources according to claim 1, characterized in that: The bottom of the water-stopping curtain (5) extends downward into the underground weakly weathered rock layer, and its two sides extend outward into the mountain strata.

9. A method for controlling groundwater pollution from a valley-type historical pollution source based on the control device described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Use the anti-scour panels (1) in the inlet area and the anti-scour panels (7) in the outlet area laid on the ground to guide the surface runoff and reduce the infiltration of surface water; at the same time, use the retaining wall (3) to intercept surface flash floods and play a buffering and water storage role. Step 2: The contaminated groundwater that has infiltrated is collected by the water guide wall (2) in the water inlet area. Under the combined guiding and blocking effect of the compacted clay at the bottom and the surrounding water-stopping curtain (5), all the contaminated groundwater is introduced into the buried PRB pool (4). Step 3: The groundwater entering the PRB pool (4) flows through the inlet zone (403), reduction zone (405), oxidation zone (406), and adsorption and fixation zone (407) in sequence. The heavy metals and organic matter in the groundwater are reduced, oxidized and adsorbed and fixed by the internal modular packing box (408). Step 4: The purified groundwater enters the outlet area (411), and after passing the online monitoring equipment test, it is discharged to the downstream environment through the outlet area water guide wall (6).

10. The method for controlling groundwater pollution from valley-type historical pollution sources according to claim 9, characterized in that: In step four, the pollutant concentrations in the inlet zone (403) and the outlet zone (411) are compared in real time using the online monitoring equipment to assess the reactivity of the packing material in the prefabricated modular packing box (408). When monitoring data indicates that the activity of the packing material has decreased, causing the effluent water quality to approach the critical value of exceeding the standard, open the concrete cover plate (409) on top of the PRB tank (4), lift out the deactivated prefabricated modular packing box (408) as a whole, and replace it with a new packing box.

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